package bit_0526_0312;

import java.util.LinkedList;
import java.util.Queue;
public class T5_0313 {
    private Queue<Integer> queue1;
    private Queue<Integer> queue2;
    public T5_0313() {
        queue1 = new LinkedList<>();
        queue2 = new LinkedList<>();
    }

    public void push(int x) {
        if (queue1.isEmpty()) {
            queue2.offer(x);
        } else if (queue2.isEmpty()){
            queue1.offer(x);
        } else {
            queue1.offer(x);
        }
    }

    public int pop() {
        if (empty()) return -1;
        if (!queue1.isEmpty()) {
            int len = queue1.size();
            for (int i = 0; i < len - 1; i++) {
                queue2.offer(queue1.poll());
            }
            return queue1.poll();
        } else {
            int len = queue2.size();
            for (int i = 0; i < len - 1; i++) {
                queue1.offer(queue2.poll());
            }
            return queue2.poll();
        }
    }

    public int top() {
        if (empty()) return -1;
        int tmp = -1;
        if (!queue1.isEmpty()) {
            int len = queue1.size();
            for (int i = 0; i < len; i++) {
                tmp = queue1.poll();
                queue2.offer(tmp);
            }
            return tmp;
        } else {
            int len = queue2.size();
            for (int i = 0; i < len; i++) {
                tmp =  queue2.poll();
                queue1.offer(tmp);
            }
            return tmp;
        }
    }

    public boolean empty() {
        return queue1.isEmpty() && queue2.isEmpty();
    }
}
